Polymeric conjugates of antitumor agents

Abstract

Water soluble polymeric conjugates of antitumor agents of formula (A) P-[W 2 ] p -S 0 -[W 1 ] r -[D] wherein: P is a water soluble polymer; [W 1 ] is a residue of formula —HN-Z 1 -CO— in which Z 1 represents a linear or branched C2-C12 alkylene chain or the residue of formula —C6HC—CH2—O—; [W 2 ] is a residue of formula —HN-Z2-CO— in which Z2 represents a C2-C12 linear or branched alkylene chain; p and r are 0 or 1; S0 is a peptide that selectively is cleaved at the tumor site mainly by the action of the matrix metalloproteinases gelatinase; [D] is the residue of an antitumor agent. The conjugates possess enhanced antitumor activity and decreased toxicity with respect to the free drug. A process for their preparation, useful intermediates and pharmaceutical compositions containing them are also described.

1 . A polymeric drug-conjugate of formula (A)  
       P-[W 2 ] p -S 0 -[W 1 ] r [D]  (A)  
       wherein: 
 P is a water soluble polymer;  
 [W 1 ] is a residue of formula —HN-Z-CO— in which Z 1  represents a linear or branched C 2 -C 12  alkylene chain or the residue of formula —C 6 H 4 —CH 2 —O—;  
 [W 2 ] is a residue of formula —HN-Z 2 -CO— in which Z 2  represents a C 2 -C 12  linear or branched alkylene chain;  
 p and r are 0 or 1;  
 S 0  is a peptide residue selectively cleavable at the tumor site by the action of matrix metalloproteinases and [D] is the residue of an antitumor agent:  
 
     
     
         2 . A polymeric conjugate according to  claim 1  wherein [D] is the residue of an antitumor agents bearing functional groups for the attachment of the linker W 1  or the peptide S 0  portion of the conjugate of formula (A) as defined in  claim 1;  r is 0 or [W 1 ] is the self-imolative p-aminobenzyloxycarbonyl linker, [W 2 ] is the residue of 6-aminohexanoic acid; and [P] is poly-glutamic acid, a carboxylated dextrane, carboxylated polyethylenglycols or a polymer based on N-(2-hydroxypropyl)methacryloylamide.  
     
     
         3 . A polymeric conjugate according to  claim 1  or  2  in which the peptide S 0  comprises sequences from four to five natural or synthetic amino acids.  
     
     
         4 . A polymeric conjugate according to  claim 3  wherein S 0  represents a sequence of formula:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                   Met(O)-Gly-Cys(Bn)-Leu, 
                   (SEQ ID NO: 1) 
                     
                 
                     
                     
                 
                     
                   Met(O)-Gly-Cys(Bn)-Gly, 
                   (SEQ ID NO: 2) 
                 
                     
                     
                 
                     
                   Met(O)-Gly-Cys(IBn)-Gly-Leu, 
                   (SEQ ID NO: 3) 
                 
                     
                     
                 
                     
                   Met(O)-Gly-Cys(Bn)-Trp-Gly, 
                   (SEQ ID NO: 4) 
                 
                     
                     
                 
                     
                   Met(O)-Gly-Cys(Bn)-pFIF-Gly, 
                   (SEQ ID NO: 5) 
                 
                     
                     
                 
                     
                   Met(O)-Gly-Cys(Bfl)-Gly-Gly, 
                   (SEQ ID NO: 6) 
                 
                     
                     
                 
                     
                   Met(O)-Gly-Cys(Bn)-Leu-Gly, 
                   (SEQ ID NO: 7) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-Leu, 
                   (SEQ ID NO: 8) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-Trp, 
                   (SEQ ID NO: 9) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-pFF, 
                   (SEQ ID NO: 10) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-Gly, 
                   (SEQ ID NO: 11) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-Trp-Gly, 
                   (SEQ ID NO: 12) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-pFF-Gly, 
                   (SEQ ID NO: 13) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-Gly-Gly, 
                   (SEQ ID NO: 14) 
                 
                     
                     
                 
                     
                   Smc-Gly-Cys(Bn)-Leu-Gly, 
                   (SEQ ID NO: 15) 
                 
                     
                     
                 
                     
                   Smc-Gly-Leu-Trp, 
                   (SEQ ID NO: 16) 
                 
                     
                     
                 
                     
                   Smc-Gly-Tha-Trp, 
                   (SEQ ID NO: 17) 
                 
                     
                     
                 
                     
                   Smc-Gly-Met-Trp, 
                   (SEQ ID NO: 18) 
                 
                     
                     
                 
                     
                   Smc-Gly-Tha-Trp-Gly, 
                   (SEQ ID NO: 19) 
                 
                     
                     
                 
                     
                   Smc-Gly-Met-Trp-Gly, 
                   (SEQ ID NO: 20) 
                 
                     
                     
                 
                     
                   Leu-Gly-Cys(lRn)-Leu, 
                   (SEQ ID NO: 21) 
                 
                     
                     
                 
                     
                   Leu-Gly-Cys(Bn)-Gly, 
                   (SEQ ID NO: 22) 
                 
                     
                     
                 
                     
                   Leu-Gly-Cys(Bn)-Leu-Gly, 
                   (SEQ ID NO: 23) 
                 
                     
                     
                 
                     
                   Leu-Gly-Cys(Bn)-Gly-Gly, 
                   (SEQ ID NO: 24) 
                 
                     
                     
                 
                     
                   Leu-Gly-Leu-Leu, 
                   (SEQ ID NO: 25) 
                 
                     
                     
                 
                     
                   Leu-Gly-Leu-Trp, 
                   (SEQ ID NO: 26) 
                 
                     
                     
                 
                     
                   Leu-Gly-Leu-Leu-Gly or 
                   (SEQ ID NO: 27) 
                 
                     
                     
                 
                     
                   Leu-Gly-Leu-Trp-Gly. 
                   (SEQ ID NO: 28) 
                 
                     
                     
                 
             
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         5 . A polymeric conjugate according to  claim 4  wherein S 0  represents a sequence of formula: Met(O)-Gly-Cys(Bn)-Leu (SEQ ID NO: 1), Met(O)-Gly-Cys(Bn)-Gly (SEQ ID NO: 2), Met(O)-Gly-Cys(Bn)-Gly-Gly (SEQ ID NO: 6), Met(O)-Gly-Cys(Bn)-Leu-Gly (SEQ ID NO: 7), Smc-Gly-Cys(Bn)-Leu (SEQ ID NO: 8), Smc-Gly-Cys(Bn)-Gly (SEQ ID NO: 11), Smc-Gly-Cys(Bn)-Gly-Gly (SEQ ID NO: 14), Smc-Gly-Cys(Bn)-Leu-Gly (SEQ ID NO: 15), Leu-Gly-Cys(Bn)-Leu (SEQ ID NO: 21), Leu-Gly-Cys(Bn)-Gly (SEQ ID NO: 22), Leu-Gly-Cys(Bn)-Leu-Gly (SEQ ID NO: 23), Leu-Gly-Cys(Bn)-Gly-Gly (SEQ ID NO: 24), Leu-Gly-Leu-Leu (SEQ ID NO: 25) or Leu-Gly-Leu-Leu-Gly (SEQ ID NO: 27).  
     
     
         6 . A polymeric conjugate according to any one of the preceding claims wherein the antitumor agent [D] is a cytotoxic agent belonging to the class of vinca alkaloids, anthracyclines, taxanes, cytotoxic nucleosides, camptothecins, podophyllotoxins, or alkylating agents.  
     
     
         7 . A polymeric conjugate according to  claim 6  wherein the antitumor agent [D] is 4-deacetyl-vinblastine, 4-deacetyl-vincristine, vindesine, doxorubicin, 4′-epidoxorubicin, daunorubicin, 4-demethoxy-daunorubicin, 4′-deoxy-4′-iododoxorubicin, 3′-(2-methoxymorpholino) doxorubicin, paclitaxel, docetaxel, 5-fluorouracil, camptothecin, 7-ethyl-10-hydroxycamptothecin, 9-aminocamptothecin, etoposide or estramustine.  
     
     
         8 . A polymeric conjugate according to any one of the preceding claims wherein [P] is a water soluble polymer based on N-(2-hydroxypropyl)methacryloylamide.  
     
     
         9 . A process for preparing a polymeric conjugate as defined in  claim 1 , which process comprises reacting a compound of general formula (1) or a corresponding salt derivative of formula (1′):  
       H-[W 2 ] p -S 0 -[W 1 ] r -[D]  (1) RH H-[W 2 ] p -S 0 -[W 1 ] r -[D]  (1′)  
       wherein [W 1 ], [W 2 ], p, r, S 0  and [D] are as defined in  claim 1;  and RH is an acid, with a polymer P1 bearing suitable functional groups for the coupling with compounds (1) or (1′).  
     
     
         10 . A process according to  claim 9  in which the suitable functional groups on polymer [P1] for the attachment of a compound (1) or (1′) as defined in  claim 9  comprise carboxyl groups or activated carboxyl groups.  
     
     
         11 . An antitumor derivative of formula (1) or the corresponding salt derivative of formula (1′) as defined in  claim 9 .  
     
     
         12 . A process for preparing a compound of formula (1) or (1′) as defined in  claim 11 , which process comprises 
 removing the N-protecting group from a derivative of formula (2);  
 R 2 -[W 2 ] p -S 0 -[W 1 ] r -[D]  (2)  
  wherein [W 1 ], [W 2 ], p, r, [D] and S 0  are as defined in  claim 9 , and R 2  represents an amino-protecting group and  
 optionally converting a resultant compound of general formula (1′) into the corresponding free amino derivative (1) by mild basic treatment.  
 
     
     
         13 . A process according to  claim 12  in which the removal of the N-protecting group is carried out in acidic conditions, and R 2  represents Boc (tert-butoxycarbonyl), Fmoc, triphenylsilyl, diphenylmethylene or triphenylmethyl group.  
     
     
         14 . A polymeric drug-conjugate according to  claim 1  which comprises a water soluble polymer [P] consisting of: 
 (i) from 85 to 97 mol % of N-(2-hydroxypropyl)methacryloylamide units represented by formula (25)  
                     
 (ii) from 3 to 15 mol % of units represented by formula (26)  
                     
  in which [W 1 ], [W 2 ], p, r, [D] and S 0  are as defined in  claim 1 ,  
 (iv) from 0 to 12 mol % of N-methacryloyl-glycine or N-(2-hydroxypropyl) methacryloyl-glycinamide units represented by formula (27)  
                     
  wherein R 3  represents a hydroxy group or a residue of formula  
 —NH—CH 2 —CH(OH)—CH 3 .  
 
     
     
         15 . A process for preparing a drug-conjugate as defined in  claim 14 , which process comprises reacting a compound of formula (1) or (1′) as defined in  claim 9  with an activated water soluble polymer (P1′) consisting essentially of: 
 (i) from 85 to 97 mol % of N-(2-hydroxypropyl)methacryloylamide units represented by formula (25) as defined in  claim 14 , and  
 (ii) from 3 to 15 mol % of N-methacryloyl-glycyl units represented by formula (28)  
                     
  wherein R 4  is the residue of an active ester, and optionally displacing the remaining active ester groups with 1-amino-2-propanol.  
 
     
     
         16 . A pharmaceutical composition comprising a pharmaceutically acceptable diluent or carrier and, as active ingredient, a polymeric conjugate as defined in any one of  claims 1  to  8  or  14  or a compound of formula (1) or (1′) as defined in  claim 11 .  
     
     
         17 . A polymeric conjugate as defined in any one of  claims 1  to  18  or  14  or a compound of formula (1) or (1′) as defined in  claim 11  for use in a method of treatment of the human or animal body by therapy.  
     
     
         18 . Use of a polymeric conjugate as defined in any one of  claims 1  to  8  or  14  or a compound of formula (1) or (1′) as defined in  claim 11   13  in the manufacture of a medicament for treating leukemia or a solid tumor.  
     
     
         19 . Use according to  claim 18 , wherein the solid tumor is a colon, colo-rectal, ovarian, mammary, prostate, lung or kidney tumor or a melanoma.